阅读说明：本技术 一种钌掺杂碳纳米管复合材料的制备方法及其在微生物电解池阴极方面的应用 (Preparation method of ruthenium-doped carbon nanotube composite material and application of ruthenium-doped carbon nanotube composite material in aspect of microbial electrolysis cell cathode ) 是由 温珍海 向利娟 次素琴 赵志锋 戴玲 郭可鑫 于 2020-04-28 设计创作，主要内容包括：本发明公开了一种利用自制的钌纳米粒子负载碳纳米管复合材料(Ru/CNTs)用于提高双室微生物电解池碱性阴极制氢效率的方法,归属于材料的制备领域和微生物电化学领域。即用水合三氯化钌和商用碳纳米管作为Ru源和C源,使用传统的硼氢化钠厌氧法制作了Ru<Sub>0.12</Sub>/CNTs复合材料,并应用于微生物电解池阴极催化阴极氢气的产生,并通过控制微生物电解池的启动步骤,改变阴极液中氢氧化钾的浓度,从而提高氢气产率。本发明优点：使用Ru<Sub>0.12</Sub>/CNTs-CC做MECs的阴极,同时改变阴极液中KOH的浓度,极大地提高了氢气产率和效率,且材料的制备过程简单,产氢能耗较低,故该阴极具有较大的应用潜力。(The invention discloses a method for improving hydrogen production efficiency of an alkaline cathode of a double-chamber microbial electrolytic cell by utilizing a self-made ruthenium nanoparticle loaded carbon nanotube composite material (Ru/CNTs), belonging to the field of material preparation and the field of microbial electrochemistry. Namely, ruthenium trichloride hydrate and commercial carbon nano tube are used as a Ru source and a C source, and Ru is prepared by using a traditional sodium borohydride anaerobic method 0.12 The CNTs composite material is applied to the generation of cathode hydrogen catalyzed by a cathode of a microbial electrolysis cell, and the concentration of potassium hydroxide in catholyte is changed by controlling the starting step of the microbial electrolysis cell, so that the hydrogen yield is improved. The invention has the advantages that: using Ru 0.12 the/CNTs-CC is used as the cathode of the MECs, the concentration of KOH in catholyte is changed, the hydrogen yield and efficiency are greatly improved, the preparation process of the material is simple, and the energy consumption for hydrogen production is low, so that the cathode has great application potential.)

1. A preparation method of a ruthenium-doped carbon nanotube composite material and an application of the ruthenium-doped carbon nanotube composite material in the aspect of a cathode of a microbial electrolytic cell are characterized by comprising the following steps:

(1) domestication of microorganisms:

after inoculating liquid is added into Microbial Fuel Cells (MFCs), sodium acetate is taken as an electron donor at the anode, potassium ferricyanide is taken as an electron acceptor at the cathode, and different external resistors are respectively connected in sequence to acclimate and culture microorganisms until the microorganisms are stable.

(2)Ru_0.12Preparation of/CNTs catalyst:

dissolving ruthenium trichloride hydrate in a suspension dispersed with carbon nano tubes, stirring uniformly, heating to 80 ℃ under the condition of introducing argon, adding a sodium borohydride solution, keeping reacting for 2 hours, naturally cooling to room temperature, repeatedly washing with deionized water and absolute ethyl alcohol for several times, and drying for later use.

(3) Preparation of electrolytic cell (MECs) cathodes for microorganisms:

ru_0.12the/CNTs composite material is uniformly dispersed in Nafion (5%), a mixed solution of deionized water and absolute ethyl alcohol to form slurry, the slurry is uniformly coated on Carbon Cloth (CC) and is naturally dried for standby, and Ru is used_0.12The loading amount of/CNTs is 5mg cm^-2。

(4) Start-up of Microbial Electrolysis Cells (MECs):

after the microorganisms are acclimated and stabilized by MFCs, the MFCs are connected with an external power supply, and the cathode is replaced by Ru_0.12The method comprises the steps of self-making a cathode by CNTs-CC, starting a microbial electrolytic cell by catholyte according to a certain KOH concentration gradient, collecting voltages at two ends of an external resistor by a data collector, and collecting generated hydrogen by a drainage method.

2. The method according to claim 1, wherein the applied resistance is 1000 Ω,820 Ω,510 Ω,330 Ω,200 Ω,100 Ω,51 Ω,24 Ω,10 Ω,7.5 Ω, and carbon brushes are used for both cathode and anode.

3. The method for preparing ruthenium doped carbon nanotube composite material and its application in microbial electrolysis cell cathode as claimed in claim 1, wherein (1) stable current of MFCs reaches 13.23 ± 0.55 mA.

4. The method for preparing ruthenium doped carbon nanotube composite material and the application thereof in the aspect of cathode of microbial electrolysis cell according to claim 1, wherein (2) the mass ratio of the ruthenium trichloride hydrate to the carbon nanotube is 12: 5.

5. The method for preparing ruthenium-doped carbon nanotube composite material according to claim 1 and the use thereof in the cathode of microbial electrolysis cell, wherein (3) the area of CC is 2cm²The appropriate CC area facilitates placing the CC in a graduated tube that collects hydrogen using a drainage method.

6. The method for preparing a ruthenium-doped carbon nanotube composite material according to claim 1 and the use thereof in a cathode of a microbial electrolysis cell, wherein (4) the voltage applied to convert MFCs into MECs is 0.8V, the resistance is 7.5 Ω, and the cultivation temperature is 20 ℃ to 35 ℃.

7. The method for preparing a ruthenium-doped carbon nanotube composite material and the application thereof in the aspect of microbial electrolysis cell cathode according to claim 1, wherein (4) the hydrogen production effect of the Ru/CNTs-CC cathode is the best when the concentration of KOH is 1.0M.

8. The method for preparing ruthenium doped carbon nanotube composite material and its application in microbial electrolysis cell cathode as claimed in claim 1, wherein (4) before starting MECs, nitrogen is introduced into MFCs for 15min to ensure the oxygen-free environment of hydrogen evolution reaction and inhibit methane generation.

9. The preparation method of the ruthenium-doped carbon nanotube composite material and the application of the ruthenium-doped carbon nanotube composite material in the aspect of the cathode of the microbial electrolysis cell according to claim 1, wherein (4) the time of one cycle of hydrogen production by MECs is controlled within 40-130 h, and the highest hydrogen yield can reach 0.167 +/-0.089 m³m^-2d^-1。

Technical Field

The invention relates to the field of material preparation and the technical field of microbial-assisted electrochemistry, in particular to the field of hydrogen production of a catalytic microbial electrolytic cell for preparing a composite material.

Background

With the depletion of fossil fuels, countries around the world have been devoted to the study of other types of energy. As a low-carbon and zero-carbon energy source, the heat value of hydrogen energy is high, and the product is clean and is distinguished from other types of energy sources. Products such as hydrogen energy automobiles, hydrogen fuel cells and the like are bridges for communicating electrochemical and hydrogen energy systems. How to produce hydrogen with high efficiency and low cost becomes a research hotspot of people. The photocatalytic and electrocatalytic decomposition of water to produce hydrogen and oxygen is the most common means. But each has some disadvantages. For example, photocatalysis has the defects of low light utilization rate of hydrogen production in a visible light range, no response to dark conditions and the like; the electrocatalytic decomposition of water to produce hydrogen requires consumption of electric energy and requires excellent electrocatalytic materials. How to produce hydrogen with low energy consumption and high efficiency becomes a key problem to be solved by electrocatalysis hydrogen production.

A Microbial Electrolysis Cell (MECs) is an electrochemical device developed on the basis of a microbial fuel cell, water can be electrolyzed to obtain hydrogen by additionally applying 0.25-1.0V of voltage with the assistance of electrochemical active bacteria, a double-chamber reactor designed in 2005 by L ogan and the like is firstly reported as a hydrogen production system, in the development process of microbial electrolysis cell hydrogen production in recent ten years, a phosphate buffer system with mild and near-neutral conditions is mostly adopted for a cathode electrolyte.

Disclosure of Invention

The purpose of the invention is: provides a preparation method of a ruthenium-doped carbon nanotube composite material and application thereof in the aspect of microbial electrolysis cell cathodes, and a new method for improving the hydrogen production efficiency of the alkaline cathodes of the double-chamber microbial electrolysis cell is obtained by researching the appropriate catalytic conditions. The method comprises the following steps:

(1) domestication of microorganisms:

the Microbial Fuel Cells (MFCs) are glass containers with the anode and the cathode both being 150m L, the middle is connected by a Proton Exchange Membrane (PEM) and an external resistor to form a closed loop, 20m L is added into the anode, the anaerobic and aerobic mixture from a local municipal sewage treatment plant is used as inoculation liquid, sodium acetate is used as an electron donor, potassium ferricyanide is used as an electron acceptor, different external resistors are respectively connected into the cathode in the sequence of 1000 omega, 820 omega, 510 omega, 330 omega, 200 omega, 100 omega, 51 omega, 24 omega, 10 omega and 7.5 omega to acclimate and culture microorganisms to be stable, and the stable current peak value of the MFCs can reach 13.23 +/-0.55 mA.

(2)Ru_0.12Preparation of/CNTs catalyst:

0.12g of ruthenium trichloride hydrate (RuCl)₃.x H₂O) is dissolved in 50m L suspension dispersed with 0.05g of Carbon Nanotubes (CNTs), stirred for 0.5h by using a magnetic stirrer and then poured into a three-neck flask, the temperature is raised to 80 ℃ under the condition of introducing argon, 10m L (5 percent by weight) of sodium borohydride solution is added dropwise to keep reacting for 2h, the mixture is naturally cooled to room temperature, and the mixture is repeatedly washed for a plurality of times by deionized water and absolute ethyl alcohol and dried for later use.

(3) Preparation of electrolytic cell (MECs) cathodes for microorganisms:

mixing 10mg of Ru_0.12the/CNTs composite material is uniformly dispersed in a mixed solution of 500 mu L Nafion (5% 50 mu L), deionized water (300 mu L) and absolute ethyl alcohol (150 mu L), and Ru is added_0.12the/CNTs composite material is evenly coated on Carbon Cloth (CC) with the thickness of 1cm × 2cm, and is naturally dried for standby, Ru_0.12The loading amount of/CNTs is 5mg cm^-2。

(4) Start-up of Microbial Electrolysis Cells (MECs):

after the microorganisms are domesticated and stabilized by the MFCs, the MFCs are accessed to a 0.8V external power supply, and the method is that the positive electrode of the power supply is connected with a 7.5 omega external resistor and is connected to the anodes of the MECs; the negative pole of power connects the negative pole of MECs, and the MECs negative pole adopts Ru/CNTs-CC self-made negative pole, and the microbial electrolysis cell is started gradually to catholyte according to certain KOH concentration gradient (0.1M PBS, 0.1M KOH, 0.5M KOH and 1.0M KOH), collects the voltage at the both ends of external resistance with the data collection station, and collects the hydrogen volume that produces with the drainage method.

The method for improving the hydrogen production efficiency of the alkaline cathode of the double-chamber microbial electrolytic cell has the advantages that: the cathode of Microbial Electrolysis Cells (MECs) generally adopts a neutral phosphate buffer system, and the hydrogen production efficiency is low. The invention adopts self-made Ru_0.12The CNTs composite material modified MECs cathode uses the alkaline electrolyte with different concentration gradients, so that the application range of the cathode material is widened, the hydrogen production efficiency is greatly improved, and the hydrogen production cost is saved.

Drawings

FIG. 1 shows Ru of Ru-doped carbon nanotube_0.12Electron microscope scanning image of/CNTs composite material;

FIG. 2 shows Ru doped carbon nanotubes_0.12XRD pattern of/CNTs composite material;

FIG. 3 shows Ru in MECs_0.12The current diagram generated by different catholyte under the external resistance of 7.5 omega and the applied voltage of 0.8V of the/CNTs-CC cathode electrode;

Detailed Description

The invention is further explained by the embodiment with the attached drawings, the preparation method of the ruthenium doped carbon nano tube composite material and the application of the ruthenium doped carbon nano tube composite material in the aspect of the cathode of the microbial electrolytic cell are as follows,

(1) domestication of microorganisms:

microbial Fuel Cells (MFCs) are glass containers with the anode and cathode both being 150M L, the middle is connected by a Proton Exchange Membrane (PEM) and an external resistor to form a closed loop, 20M L of anaerobic and aerobic mixture from a local municipal sewage treatment plant is added into an anode to serve as inoculation liquid, 130M L of anode liquid taking sodium acetate as an electron donor is added, 0.1M phosphate buffer solution and 0.1M K of cathode liquid are used as the catholyte₃[Fe(CN)₆]The volume ratio of the mixed solution of (1) to (1). Inoculating different external resistors to acclimatize and culture microorganisms to be stable and stable current of MFCs respectively according to the sequence of 1000 omega, 820 omega, 510 omega, 330 omega, 200 omega, 100 omega, 51 omega, 24 omega, 10 omega and 7.5 omegaThe peak value can reach 13.23 +/-0.55 mA, and the current generated by the microbial electrolytic cell during the acclimation period is shown in the attached figure 1.

(2)Ru_0.12Preparation of/CNTs catalyst:

0.12g of ruthenium trichloride hydrate (RuCl)₃.x H₂O) is dissolved in 50m L suspension liquid with 0.05g of Carbon Nano Tubes (CNTs) dispersed therein, after magnetic stirring is carried out for 0.5h, the mixed solution is poured into a three-neck flask, the three-neck flask and the three-neck flask are put into an oil bath pot together, under the condition of introducing argon, the temperature is raised to 80 ℃,10 m L (5 percent by weight) of sodium borohydride solution is added dropwise, the reaction is kept for 2h, the mixture is naturally cooled to the room temperature, the mixture is repeatedly washed for a plurality of times by deionized water and absolute ethyl alcohol after being dried, and the mixture is ground by a mortar to form uniform powder, thus obtaining Ru_0.12/CNTs composite material. The scanning electron microscope is shown in figure 1, and the XRD is shown in figure 2.

(3) Preparation of electrolytic cell (MECs) cathodes for microorganisms:

accurately weighing 10mg of Ru/CNTs composite material, dispersing in a mixed solution of 500 mu L Nafion (5% 50 mu L), deionized water (300 mu L) and absolute ethyl alcohol (150 mu L), performing ultrasonic treatment for 30min to form uniform slurry, uniformly coating the slurry on CC (1 cm × 2 cm), and naturally drying for later use to prepare Ru/CNTs composite material_0.12CNTs-CC cathode, Ru_0.12The loading amount of/CNTs is 5mg cm^-2。

(4) Start-up of Microbial Electrolysis Cells (MECs):

after the microorganisms are domesticated and stabilized by the MFCs, the MFCs are accessed to a 0.8V external power supply, and the method is that the positive electrode of the power supply is connected with a 7.5 omega external resistor and is connected to the anodes of the MECs; the negative electrode of the power supply is connected with the cathodes of the MECs, and the cathodes of the MECs adopt Ru_0.12/CNTs-CC self-made cathode, catholyte gradually starts a microbial electrolytic cell according to a certain KOH concentration gradient (0.1M PBS, 0.1M KOH, 0.5M KOH and 1.0M KOH), voltage at two ends of an external resistor is collected by a data collector, the volume of generated hydrogen is collected by a drainage method, and the MECs use Ru (ruthenium-doped zinc sulfide)_0.12The currents generated by the different catholyte at an external resistance of 7.5 omega and an applied voltage of 0.8V for the/CNTs-CC cathode electrode are shown in figure 3.